Various breathing systems have been developed to provide means by which air or other gases can be administered to a patient from a gas source such as a compressed gas container or directly from the atmosphere. For example, it is often necessary during the treatment of a patient to administer an anesthetic mixture of gases from an anesthesia machine. Moreover, it is sometimes necessary to administer pulmonary resuscitation to a patient following surgery or when voluntary breathing has been interrupted due to an illness or injury.
As known by those skilled in human physiology, respiration involves the exchange of gases in the lungs. Breathing can be described as the mechanical process by which air is drawn into and expelled from the lungs by muscular contractions in the rib cage and diaphragm. Inhalation is an active process whereby the thoracic volume is increased through muscle contraction. Exhalation is a passive process wherein the contracted muscles relax, causing the thoracic volume to be reduced. This reduction in lung volume raises the air pressure inside the lungs such that air in the lungs is expelled through the airways into the atmosphere.
One problem inherent in the exhalation of air from the lungs which has received considerable attention recently due to an increased knowledge of infectious processes and due to the discovery of new, highly contagious viruses, is crosscontamination caused by the expiration of an infectious organism. More specifically, it is known that exhalation often produces an aerosol of tiny water droplets in which an infectious agent may reside. It is also known that viruses such as influenza and like are commonly transferred from one individual to another, a process referred to as cross-infection, as the direct result of the exhalation of infectious aerosol. In essence, the infectious agent is able to survive outside of the body in these tiny water droplets. Moreover, these droplets may deposit on a substratum where they remain biologically active for some time. This latter phenomenon may lead to cross infection due to surface contamination. In my U.S. patent application Ser. No. 026,067, filed Mar. 16, 1987, I disclose novel breathing systems which utilize integral bacterial/viral filters that prevent contamination of breathing systems to reduce the possibility of cross-infection. The present invention, as will be explained more fully below, provides yet another novel solution to the problem of contamination of breathing systems by exhalation or expiration of infectious agents which is a significant problem with most conventional breathing apparatus.
In particular, there are a number of prior art breathing valve assemblies which may be used with a manual resuscitation bag or the like. One such valve assembly includes a complicated set of springs, balls and valve seats which responds to air pressure differentials in the breathing system to open and close air passages. These devices are not only expensive to manufacture, but the ball valves are particularly sensitive to gravitational forces rendering the valve assembly position sensitive. Thus, the patient must be precisely positioned to accommodate the position sensitivity of the valve. In addition, these prior art breathing valve assemblies generally provide substantial resistance to air flow, making it difficult to compress the resuscitation bag during operation. As those skilled in the art will appreciate, ease of bag compression is a highly desirable attribute of manual resuscitators.
Also, it is also known that many conventional manual resuscitation systems require an intake valve on the bag in order that the resuscitator bag may be refilled with air or air/oxygen.
The present invention solves these prior art problems in a manner in which transmission of pathogens from the patient's aerosol to the resuscitation bag can be reduced or eliminated, thus making the resuscitator bag reusable and reducing resuscitator costs to hospitals.